Project Summary/Abstract Hip Chondromics: comprehensive cartilage characterization with MR fingerprinting Femoroacetabular impingement (FAI) is a pathologic condition in which structural abnormalities of the femoral head-neck junction and/or acetabulum lead to a mechanical blockage in the hip joint that compromises the terminal range of motion. If the impingement is left untreated, it can cause cartilage damage and lead to hip osteoarthritis. The goal of this project is to demonstrate the utility of multi-parametric quantitative magnetic resonance (MR) imaging for the clinical management of FAI and to develop the technology necessary to translate it into clinical routine. We will conduct a longitudinal study using intraoperative cartilage assessment and clinical outcome measures to show, for the first time, that a combination of dGEMRIC (i.e., cartilage T1 mapping in the presence of gadolinium contrast agent) and T2 mapping can identify prognostic factors associated with successful FAI arthroscopy and improve surgical patient selection. Concurrently, we will develop a method to map multiple MR parameters simultaneously in one single scan and enable comprehensive morphologic and biochemical characterization of the hip cartilage without exogenous contrast agents (i.e., ?Hip Chondromics?). This new technique will employ concepts from magnetic resonance fingerprinting (MRF) to create B1 insensitive 3D multi-parametric maps with isotropic resolution in clinically feasible scan time. In particular, we will develop a new strategy to simultaneously quantify T1, T2 and magnetization transfer (MT) rate using MR fingerprints, since the combination of these three parameters has demonstrated a strong correlation (r2 > 0.8) with direct measurements of cartilage biochemical components. To facilitate clinical translation of quantitative MR parameters in FAI, we will also develop and disseminate new software tools for automated segmentation of the hip cartilage, extraction of relevant diagnostic measures and optimized data visualization. Our technique will enable accurate preoperative assessment of articular cartilage damage, predict risk for progression, identify patients who will benefit from arthroscopy, and monitor the effectiveness of joint preserving surgeries, as well as cartilage repair procedures, in preventing hip osteoarthritis. Successful completion of this project will provide a new classification system for articular cartilage lesions in the hip, based on quantitative MR imaging, which is intrinsically more sensitive to early cartilage damage than standard X-ray and magnetic resonance imaging. Our proposed MRF technique will enable in vivo rapid volumetric multi-parametric mapping that could also have an impact for quantitative imaging in other anatomical structures such as, for example, the brain.